The Synthesis of Tritium-Labeled 16α,17α-Cyclohex-3′-eno-progesterone as Probe for the Study of Steroid–Receptor Binding

Tritium-labeled 16α,17α-cyclohex-3′-en-pregn-4-en-3,20-dione (16α, 17α-cyclohex-3′-eno-progesterone) with specific activity of 44 Ci/mmol, required in studying of binding with progesterone receptors, has been obtained by homogenous catalytic hydrogenation of 16α,17α-cyclohex-3′-eno-pregna-1,4-dien-3,20-dione with gaseous tritium and subsequent separation of the mixture by HPLC. Biological testing has shown it to bind to rat uterine progesterone receptor with an affinity comparable with that of progesterone itself.